The Penrith Panthers are likely to be without Tevita Pangai Junior for the grand final.

It has been something of a whirlwind couple of months for the big forward, who was at the Broncos to begin 2021.

He was then told he wouldn't be at the club in 2022, eventually signing with the Canterbury Bulldogs, before linking with the Penrith Panthers on a short-term deal to chase a premiership at the end of this season.

However, a medial injury on his own home ground out of Saturday's gruelling and physical preliminary final victory over the Melbourne Storm could stop him playing in the decider.

He was seen in a knee brace on Monday at the Panthers' media day.

It's understood the Panthers are yet to officially put a line through Pangai Junior yet, meaning he could well still be named in the 21-man squad tomorrow at 4pm.

He is however, due to have scans today, meaning an answer should be available on Tuesday morning.

The injury occurred late in the game as Pangai Junior attempted to make a tackle before being awkwardly pushed into teammate Matt Burton, causing his leg to buckle.

Should Pangai Junior be ruled out, he will likely be a straight swap with the returning Moses Leota after Pangai Junior was brought into the starting side for the injured Leota. It also means Spencer Leniu would likely retain his place for the decider.

Leota himself has struggled with injuries throughout the finals, missing both a qualifying final against the Rabbitohs and Saturday's nail-biter with the Storm.

The Panthers haven't lost their sense of humour though despite the injury concerns, with Brian To'o arriving at the media day in a wheelchair with his ankle strapped and in a brace.

The Panthers will take on the South Sydney Rabbitohs in this Sunday's NRL grand final at Suncorp Stadium in Brisbane, with kick-off scheduled for 7:30pm (AEST).